"It's so hard to get to the top of the charts, you push yourself so much, it feels like you should push a little further to celebrate once you do," Eldredge says, "I like to push myself to live life to the fullest."

On an expedition arranged through the non-profit group Rock the Ocean, he and several of his buddies took the plunge Wednesday to swim with the sharks – cage not included. "Getting past the fear of breathing underwater was the first step," he told PEOPLE Country exclusively after the dive. "But when you get to the bottom it's so peaceful and quiet. Our second dive was to this beautiful old shipwreck, and sharks were everywhere."

"The people who ran it told us the sharks are curious and would be swimming all around, but respect them and be smart and we'd be fine," he says. "I decided right away to be smart!"

He was also prepared – for a great photo op! "I love going to No. 1 parties, everybody gets their plaques and gets their pictures taken," he says. "I had this idea to get the No. 1 plaque and gold single plaque and take them down with us. I swam over to the shipwreck with the plaques and the sharks, and we snapped some photos. It was such a surreal feeling. I am definitely hooked on sharks!"

So what will he do if his latest single, "Mean to Me," which was just released this week, takes the top spot? Eldredge says he's not ready to think about that yet.

"I just want to enjoy this one right now," he says. "Today was the best day of my life, for real! Tonight is all about a couple of drinks at a local Bahamian bar, celebrating life and what we just accomplished. A fan sent me a Jaws tank top, so I might be wearing that. I'm a lucky guy to be able to do this kind of thing, and a lucky guy to be on dry land ready to drink some rum."